This invention is directed to improved lubricant and fuel compositions comprising alkylated thiophene lubricant fluids alone or in combination with synthetic or mineral oils, and to mineral or synthetic lubricant oil or hydrocarbyl or hydrocarbloxy fuel compositions containing minor amounts of said alkylated thiophenes as multifunctional additives therefor.
Polyphenyl sulfides and polyphenyl thioethers are known and have been used as lubricants/additives in special applications. Polyphenyl sulfides suffer from very high cost due to difficult synthesis and have poor low-temperature properties. Polyphenyl ethers are known for their high temperature properties as noted in D. Klamen's "Lubricants and Related Products" Verlag Chemie, 1984, pp. 116-121, and references contained therein, and also in, for example, the product bulletin for the commercial polyphenyl ether, OS-124 by Monsanto.
G.B. 1,093,945 to Neale is directed to the alkylation of diphenyl sulfides in the presence of aluminum chloride catalysts.
Incorporation of linear alkyl groups into diphenyl sulfide eliminates both of the above problems and provides a novel, relatively inexpensive lubricant having excellent low-temperature properties. The use of these adducts as a lubricant or lubricant additive in either mineral or synthetic lubricant has been recently disclosed (PD 90-145, L. R. Rudnick).
The principal limitation of getting monoalkylated fluids of diphenyl sulfide using lower olefins is obtaining high viscosity index. Alkylation of thiophene with hexadecene provides a monoalkylated adduct having a viscosity of 2.8 cSt and a VI of &gt;125. This opens a wider range of application areas for alkyl aromatic sulfur-containing lubricating fluids.
Many alkylation processes are known in the art and the alkylation methods of much of the prior art are primarily directed to polysubstituted or polyalkylated products. See, for example, JA 5557391 to Matsumura which discloses the dialkylation of diphenyl ethers over aluminum chloride. U.S. Pat. No. 4,395,372 to Klutz discloses the alkylation of benzene over a zeolite to obtain a predominantly polyalkylated product unless the alkylation takes place in the presence of sulfur dioxide. On the other hand U.S. Pat. No. 4,664,829 to Arakawa alkylates a mixture of materials to obtain both mono- and polysubstituted material. Arakawa uses Friedel-Crafts type catalysts. Garces, U.S. Pat. No. 4,891,448 discloses the alkylation of polycyclic aromatics over natural zeolites such as mordenite, offretite and gmelinite.
Clark, U.S. Pat. No. 3,395,101, is directed to the use of tertiary alkyl thiophenols as lubricants and hydraulic fluids. However, these fluids comprise mixtures of mono- and dialkylthiophenes.
Shoemaker, et al. is directed to lubricants and to lubricant additives. The active material in the fluids of Shoemaker et al. appear to be compounds having one or more nitrogen groups in heterocyclic ring structures such as azoles and azines. The thiophenes disclosed are useful as additives for corrosion inhibition, etc.
We now disclose the preparation and use of monoalkylated thiophenes as a new class of lubricating fluids. These fluids have the advantages of alkylated diphenyl sulfides in that the polar sulfur provides excellent additive solubility and good lubricating properties. To the best of applicant's knowledge and belief, the herein described alkylated compounds have not been used previously as lubricants or additives.